A battery has been conventionally and widely used as a means for supplying electric power to an electrical device. Conventionally, primary batteries such as a manganese dry cell, an alkaline manganese dry cell, a zinc-air battery, and the like, and secondary batteries such as a nickel-cadmium (Ni—Cd) battery, a nickel-hydrogen (Ni—H) battery, a lithium ion battery, and the like are used as batteries. Among the foregoing batteries, the zinc-air battery has advantages of providing a relatively high voltage of 1.4 V and having high energy density and large discharge capacity. Further, the zinc-air battery exhibits an almost constant discharge characteristic until electrical discharge of the zinc-air battery is completed, and the zinc-air battery is considered as a battery capable of replacing a mercury battery of which usage is suppressed owing to containing a heavy metal.
Resulting from the foregoing advantages, the zinc-air battery has been applied to various fields such as military weapons and industrial equipment, and the inventors of the present invention have sought for a strategy to apply the zinc-air battery to a device or equipment, such as marine rescue equipment, exposed to seawater and, to this end, it is necessary to find solutions to the following points.
Primarily, the marine rescue equipment is not required to operate in an ordinary situation other than emergency, but it is a very important property for the marine rescue equipment to appropriately operate in a situation in which rescue is required when a person falls into the sea, and thus it is important for the marine rescue equipment to use a battery optimized for such a property.
However, when a conventional lithium ion battery is used, electrical discharge naturally occurs in an ordinary situation other than emergency, and thus, in consideration that the lithium ion battery is usually stored for a long period of time, there is a problem in that the lithium ion battery is almost discharged at a time when an emergency situation requiring marine rescue occurs such that rescue equipment may not operate normally.
Further, even when a conventional zinc-air battery is used as a battery, the zinc-air battery is almost discharged during a storage period like the lithium ion battery due to a case in which the zinc-air battery is exposed to outside air in an ordinary situation, such that the rescue equipment may not operate normally in an emergency situation.